Explosive cartridge with lowering means



Sept. 23; 1958 c. J. BREZA ET AL EXPLOSIVE CARTRIDGE. WITH LOWERING MEANS Filed Jan. 25, 1957 INVENTORS CYRIL J. BREZA EDGAR J. SNIFFIN ATTORNEY tube and metal ends has gained acceptance.

United States Patent ice EXPLOSIVE CARTRIDGE WITH LOWERING I MEANS Cyril J. Breza, Thorofare, and Edgar J. Sniflin, Clayton, N. J., assignors to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Application January 23, 1957, Serial No. 635,879

3 Claims. (Cl. 294-93) The present invention relates to a novel lowering device and more particularly to a device adapted to facilitate the lowering of explosive charges packaged in metalended containers. I

Explosive compositions high in ammonium nitrate content are highly susceptible to deterioration by moisture, and are always packaged in water-impervious containers.

Most of the containers are metal cans, although recently the use of containers consisting of a treated paperboard When these compositions are introduced into water-containing boreholes, particularly deep boreholes where water pressure is considerable, care must be taken to prevent damage which would destroy the water tight integrity of the container. In addition, the loading must be performed in a manner minimizes the probability of the container bridging or becoming wedged in the borehole before reaching the desired depth.

For the foregoing reason, the explosive charges are seldom dropped into the borehole, but, instead, are carefully lowered by means of a lowering line. To permit attachment of lowering hooks, a bail is soldered onto at least one metal end of the container. While the bail provides a satisfactory support from the standpoint of lowering ease, the installation of the balls on each container represents an added cost to the production of the charge assembly.

Accordingly, an object of this invention is to provide a lowering device for metal-ended containers which does not require a bail on the container. A further object is to provide a readily attachable and detachable lowering device for explosive charges. Additional objects will become apparent as the invention is more fully described.

The foregoing objects are achieved when a device is provided which comprises a strip of spring steel, a pair of opposed lever arms each having one end attached to said strip at a point intermediate the midpoint and an end of said strip, and means for attaching a lowering line to about the midpoint of said strip.

To more fully illustrate the present invention, reference is now made to the accompanying drawingin which Figure 1 illustrates a side view of the device attached to a can, Figure 2 illustrates a front view of the device, and Figure 3 illustrates a top view of the device. Referring now to the figures in greater detail. A represents a metal lid on a container B of an explosive composition C. The metal lid A has projecting edges where the lid has been sealed to the container B. 1 represents a strip of spring steel, 2 is a pair of opposed lever arms, 3 is an assembly frame, 4 is a lowering rope, 6 is a milled opening through which pass the lever arms 2, and 5 is a drilled hole for lowering rope 4.

To position the device on a metal end A of a container B as shown in Figure 1, the two lever arms 2 are pressed toward each other. This movement of the arms causes the strip 1 to are, thus reducing the distance between the ends. The strip 1 is then readily inserted into the metal end A, and upon release of the lever arms 2, the

r M -2,853,334 Patent d Sept. 23, 1958 strip 1 tends to straighten, thus increasing the distance between the ends and thereby pressing the ends against the inside edges of metal end A. Preferably, the ends will be pointed, as shown in Figure 3',"'so that they will'embed themselves slightly into the edges of metal end A.

The container B can now be lowered into position, the clamping action of the spring strip 1 being of suflicient strength to support the weight of the container and contents C. When the container B has been lowered to the desired point, a jerk on the lowering line 4, releases the strip 1. As shown in the drawings, the lowering rope 4 through the frame 3 is attached to about the midpoint of the strip 1 and, when the lowering line is given a jerk, the inertia of the filled container B tends to restrain motion of the ends of strip 1, so that the tension on the midpoint tends to cause the strip 1 to are. Any arcing reduces the distance between the ends of strip 1, thus releasing the metal end A.

For example, a lowering device constructed as shown in the drawings and having a spring steel strip 0.021 inch in thickness, 0.625 inch in width and 2.437 inch in length was inserted into the metal end of a loaded container weighing 5.5 pounds, the inside diameter of the metal end being 2.321 inches. The loaded container was securely held as long as no sudden pull was applied to the lowering line, but was released immediately when the line was jerked. To illustrate the holding strength, additional weights were added to the container while it was suspended in airan average dead weight of 16 pounds was required before release occurred.

Obviously the dimensions of the various elements of the device will vary according to the dimensions and weight of the container with which the device will be used. The length of the steel strip must exceed the inside diameter of the metal end in order to provide gripping action; this excess may be as little as 1% of the inside diameter of the metal end. For maximum gripping action, the end or point of the strip should be fairly close to perpendicular to the inner wall of the metal end, i. e., the strip should not be so long that a sharp arc remains when the strip has contacted the inner walls of the metal end. A length of strip which does not exceed the inner diameter of the metal end by more than about 25% is satisfactory.

The width and thickness of the strip are interdependent i. e., for a given holding strength, .increase in width permits reduction in thickness. The strip should be of such thickness and width that the ends are not deflected sufficiently to reduce the distance between the ends to less than the diameter of the metal end by a weight equal to the weight of the container and contents. Obviously,

In the embodiment shown, the lowering rope is attached to an assembly frame. The configuration of the means of attaching the lowering rope to the approximate midpoint of the spring steel strip may be widely varied. A large ring or an eye-bolt construction will serve as well. Similarly, in the embodiment shown, the opposed lever arms have straight sections and sharp angles; smoothly curved arms would serve as well. The lever arms are opposed so that one-hand arcing of the steel strip is feasible and any configuration which permits such handling is satisfactory. Many other modifications will occur to those skilled in the art. Therefore, we intend to be limited only by the following claims.

We claim:

1. A device for lowering containers of explosives, said containers having metal ends, which comprises a substantially straight strip of spring steel, a pair of opposed lever arms rigidly attached to the same surface of said strip, the attached end of one of said lever arms being on the opposite side of the midpoint of said strip from the attached end of the second of said lever arms, and a means for connecting a lowering line to the midpoint of said strip. 2. A device as claimed in claim 1, wherein the ends of said strip form a point.

:3 A device as claimed in claim 1,-wherein said means for connecting the lowering line to the midpoint of said 4 strip comprises an assembly frame attached to said strip at the midpoint thereof and an opening through which the lever arms pass and an opening through which the lowering line passes.

References Cited in the file of this patent UNITED STATES PATENTS 1,779,291 Richardson 7. .Oct. 21, 1930 

